   (list (current-file-name)  (:line (meta form))))
 
 
-(defn compile-time-fallback-position []
-  (list (current-file-name) @fallback-line-number))
+(defn set-fallback-line-number-from [form]
+  (reset! fallback-line-number (or (:line (meta form)) (Integer. 0))))
 
 
 ;; RUNTIME POSITIONS
 ;; These are positions that determine the file or line at runtime.
-
-(defmacro line-number-known
-  "Guess the filename of a file position, but use the given line number."
-  [number]
-  `[(current-file-name) ~number])
-
-
-(defn- skip-to-rightmost-leaf
-  "When positioned at leftmost position of branch, move to the end form.
-   In a tree, that's the rightmost leaf."
-  [loc]
-  (let [end-form (zip/rightmost loc)]
-    (if (zip/branch? end-form)
-      (recur (zip/down end-form))
-      end-form)))
-
-
-(defn- replace-loc-line [loc loc-with-line]
-  (let [m (fn [loc] (meta (zip/node loc)))
-        transferred-meta (if (contains? (m loc-with-line) :line )
-                           (assoc (m loc) :line (:line (m loc-with-line)))
-                           (dissoc (m loc) :line ))]
-    (zip/replace loc (with-meta (zip/node loc) transferred-meta))))
-
 
 (defn form-with-copied-line-numbers [line-number-source form]
   (loop [loc (zip/seq-zip form)

        :else
        (vary-meta form assoc :line (:line (meta number-source)))))


                 (zip/next line-loc)))))


(defmacro line-number-known
  "Guess the filename of a file position, but use the given line number."
  [number]
  `[(current-file-name) ~number])


(defn positioned-form
  "Make sure the form is annotated with a line number, either
   its original or the given one. Takes either a number or form
